Calibration panel

ABSTRACT

The disclosed MMW wave sensing camera calibration arrangement that generally includes a millimeter wave camera that uses an energy emission calibration panel as a calibration standard. The MMW camera is positioned opposite the calibration panel in the MMW camera&#39;s field-of-view. The calibration panel is held at a constant temperature to provide a standard emission of millimeter waves that is sensed by an MMW sensor to set or otherwise calibrate the MMW camera to a baseline emissivity value corresponding to the panel. The MMW camera is linked to a microprocessor and non-transient computer memory containing a calibration routine that is configured to reset the baseline only when nothing obstructs the calibration panel&#39;s field-of-view. A visual display is linked to the MMW camera and configured to display an MMW signature of a metal object that is disposed on a person&#39;s body when the person&#39;s body is in the field-of-view, the metal object concealed by clothing worn over the person&#39;s body.

CROSS-REFERENCE TO RELATED APPLICATIONS

None

FIELD OF THE INVENTION

The present embodiments are directed to a calibration scheme for a heatsensitive camera that can be used in a public setting.

DESCRIPTION OF RELATED ART

Whether for protection or outright assault, people have been concealingweapons since before recorded history. Accordingly, personalexaminations for security have existed just short of when concealedweapons were first conceived. With today's explosion of technologyadvances, the range of weapon options is expansive. From bombs and handgrenades to guns and knives, routine pat-downs can be a dangerousproposition for security personnel. Taking into account modern-daysocial sensitivities, the intimate touch of a pat-down is not lookedupon favorably. Armed with this understanding, it should be obvious thatinnovations around pat-downs, such as metal detectors and x-ray systems,are being actively used to help reveal and thwart unwanted entrance ofconcealed weapons in secure locations without invasion of personalspace. In fact, use of metal detectors and x-ray systems are ubiquitousin airports, government buildings, hospitals, etc. Though reasonablyeffective, these detectors need to be within a couple of feet from thesubject being scanned for any hope of obtaining a signal strong enoughto adequately detect a concealed weapon. In the case of x-rays,undesirable health impact has been shown. Most metal detectors and x-raysystems are large stationary pieces of equipment that a person must walkto or through.

Hand-held metal detectors (often shaped like wands with the sensor atone end and the handle at the other) in particular require closeproximity to the subject of interest in order to detect items ofinterest. Further, only one person at a time can be scanned with thesedevices. One of the most utilized hand-held detector that can detectmetal is a wand that operates 6 inches from the person and is marketedas a long-distance metal detector.

It is to innovations related to this subject matter that the claimedinvention is generally directed.

SUMMARY OF THE INVENTION

The present embodiments are directed to a calibration panel and schemefor heat sensitive cameras.

Certain embodiments of the present invention contemplate a cameracalibration arrangement comprising a heat sensing camera having afield-of-view and a heat calibration panel comprising at least onetemperature that is essentially constant. The word ‘having’ as usedherein is to be interpreted as synonymous with ‘comprising’. The heatcalibration panel is in the field-of-view and is disposed essentially atthe right angle to a confronting panel face of the heat calibrationpanel. The heat calibration panel is at a stable or otherwise fixeddistance away from the heat sensing camera. An object cover, such as ashirt or some other garment, is configured to cover a portion of anambulatory heat producing object, which can be a person either walkingor on a cart. The ambulatory heat producing object, and by defacto, theobject cover is defined in a first location that is interposed betweenthe heat sensing camera and the heat calibration panel and the objectcover in a second location that is not in the field-of-view. Amicroprocessor that is configured to execute a calibration routine thatuses the heat calibration panel as a calibration baseline when apredetermined condition is met. The calibration routine is neverexecuted when the object cover is in the first location.

Yet other certain embodiments of the present invention envision a cameracalibration method comprising: providing a millimeter wave (MMW) sensingcamera disposed at a fixed distance from an energy emission calibrationpanel (panel) and opposing the panel, the panel in a field-of-view ofthe MMW camera. The panel being maintained at essentially a constanttemperature. Triggering a calibration routine for the MMW camera thatoperates on a processor in communication with the MMW camera. After thetriggering step, obtaining an energy emission measurement of the panelvia the MMW camera only when the panel is not obstructed from thefield-of-view. After the obtaining step, calibrating the MMW camera byadjusting an energy emission measurement level for the MMW camera tomatch the energy emission. After the adjusting step, the MMW cameraacquiring a metal object signature from a metal object that is on aperson's body, the metal object is between the person's body and the MMWcamera, the metal object is covered under clothing that covers at leasta portion of the person's body. After all of these steps, visuallydisplaying the metal object signature on a display screen linked to theMMW camera.

While other certain embodiments of the present invention imagine an MMWsensing camera calibration arrangement is envisioned comprising an MMWcamera disposed at a fixed distance from an energy emission calibrationpanel, the MMW camera is opposing a front face of the panel. The MMWcamera further defines a field-of-view that encompasses the panel. Thecalibration panel is at essentially a constant temperature. The MMWcamera having an MMW sensor comprising a baseline emissivity valuecorresponding to the panel. A microprocessor that is linked to the MMWcamera and non-transient computer memory containing a calibrationroutine that is configured to reset the baseline only when no objectobstructs the panel in the field-of-view. A visual display that islinked to the MMW camera and configured to display an MMW signature of ametal object that is disposed on a person's body when the person's bodyis in the field-of-view, the metal object concealed by clothing wornover the person's body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a line drawing of a single heat sensing camera and thermalpanel calibration arrangement consistent with embodiments of the presentinvention;

FIGS. 2A and 2B illustratively depict examining a person as they passbetween the MMW camera and the panel consistent with embodiments of thepresent invention;

FIG. 3 is a block diagram laying out the calibration scheme for the heatcamera and panel arrangement of FIGS. 2A and 2B consistent withembodiments of the present invention; and

FIG. 4 is a line drawing of yet another calibration arrangement of thepresent invention with a plurality of MMW cameras consistent withembodiments of the present invention.

DETAILED DESCRIPTION

Initially, this disclosure is by way of example only, not by limitation.Thus, although the instrumentalities described herein are for theconvenience of explanation, shown and described with respect toexemplary embodiments, it will be appreciated that the principles hereinmay be applied equally in other types of situations involving similaruses of calibration panels and heat sensitive cameras or related sensingdevices. The phrases “in one embodiment”, “according to one embodiment”,and the like generally mean the particular feature, structure, orcharacteristic following the phrase is included in at least oneembodiment of the present invention, and may be included in more thanone embodiment of the present invention. Importantly, such phases do notnecessarily refer to the same embodiment. If the specification states acomponent or feature “may”, “can”, “could”, or “might” be included orhave a characteristic, that particular component or feature is notrequired to be included or have the characteristic. As used herein, theterms “having” and “including” are considered open language and aresynonymous with “comprising”. In what follows, similar or identicalstructures may be identified using identical callouts.

Described herein are embodiments of a millimeter wave sensing cameracalibration arrangement that generally includes a millimeter wave camerathat uses an energy emission calibration panel as a calibrationstandard. Essentially all objects emit and/or reflect millimeter waves(MMWs), which can be sensed by specific MMW sensing camera systems.Different materials emit and/or reflect different concentrations of MMWsproviding an opportunity to roughly distinguish one material fromanother. For example, a metal object emits a lower concentration butreflects a higher concentration of MMWs as compared with a person'sbody. Another characteristic of MMWs is the ability to pass throughgarments without any or hardly any difficulty. Accordingly, one use ofan MMW camera is to see or otherwise identify a metal object under aperson's clothing. This makes an MMW camera a competent concealed weapondetection apparatus for screening people going into buildings, throughairports, into secure zones or areas, etc. One MMW camera set upinvolves putting an MMW camera on a fixed surface, table, or tripod thatcan screen people, suitcases, backpacks, or other like objects passingin front of it. However, like many sensing devices, the MMW sensors inthe MMW cameras tend to drift, meaning the sensed intensity of MMWscorresponding to a particular MMW baseline tends to drift away from thebaseline. One solution is to mount a calibration panel on a wall or on astand opposing the MMW camera. Because a MMW camera senses emissivity,which is influenced by temperature, the calibration panel is envisionedto be held at a constant temperature thereby emitting a known intensityof MMWs. Hence, a passive calibration arrangement envisions acalibration panel mounted on a wall or set up at a far enough distanceaway from the MMW camera for people to comfortably walk between. In thisway, a person unaware of an MMW camera and panel system, is passivelyscreened for concealed weapons by simply walking between the MMW cameraand the calibration panel. The MMW camera re-calibrates its baseline viathe panel from time to time when no one is in front of the panel. Otherembodiments of the present invention envision using the panelarrangement to also calibrate an infrared/heat sensing camera. The belowfigures illustrate some of these concepts by way of examples in the formof embodiments.

FIG. 1 is a line drawing of a single heat sensing camera and thermalpanel calibration arrangement consistent with embodiments of the presentinvention. As shown here, the heat-sensing camera is a millimeterwavelength (MMW) camera 120 pointing in the direction of a thermalcalibration panel 108. The MMW camera 120 distinguishes over other typesof cameras in that an MMW camera detects millimeter (mm) waves emittedat frequencies between 30-300 GHz. Detecting mm waves (MMWs) 103 makesthe MMW camera 120 especially good at seeing metallic objects undergarments, such as concealed weapons on a person or in a bag. The MMWcamera 120 can be coupled with an optical camera 122, which in thepresent embodiment is arranged to point in the same field-of-view 106 asthe MMW camera 120. Hence, when an MMW image is taken it can be comparedwith the optical camera image (e.g., the MMW image can be framed with,overlaid on, superimposed with, framed with, or otherwise related to theMMW image via some other kind of comparative technique). In certainconfigurations, a plurality of MMW images are stitched together todefine an MMW field-of-view 106 and then compared with an optical cameraimage, which can accommodate a situation when the MMW field-of-view 106is smaller than the optical camera field-of-view. As should beappreciated, an overlaid MMW image (or stitched together MMW images) ona corresponding optical image may improve showing a metallic objectsuperimposed over a subject of interest, such as a person potentiallycarrying a concealed weapon or a weapon in a bag. In this way, anend-user (such as TSA or police) can easily evaluate the threat of aconcealed weapon in a person's possession.

In this embodiment, the fundamental layout of the MMW camera system 120is an antenna 124 positioned in front of an electromagnetic horn 126 andthe MMW detector 129. Different configurations can accomplish the goalof collecting MMW waves 103, e.g., the horn 126 can function as theantenna 124, etc. The MMW camera system 120 detects electromagneticwaves (EMW) in the millimeter (mm) frequency range from between 30 GHzto 300 GHz. Based on principles of blackbody radiation, all objectsabove absolute zero radiate (or emit) millimeter waves (MMWs) more orless uniformly in all directions. Objects also reflect ambient MMWs inthe environment (from sources such as the sun, interior lighting, orsources that intentionally transmit MMWs) as well as self-generatedemission of MMWs due to blackbody radiation. MMWs are particularly wellsuited for identifying concealed metal weapons (or other metallicobjects) through clothing, and the like, because MMWs are long enough topenetrate clothing (compared to visible light, for instance) but shortenough to reflect off or emit from metal.

As further shown in FIG. 1, the MMW antenna 124 collects MMWs 103 (ormore specifically the MMW electromagnetic energy) coming from aparticular field-of-view 106 and directs the collected MMW energy 103 tothe MMW detector 129 via the electromagnetic horn 126. As previouslymentioned, a number of different antenna configurations are envisionedwithin the scope and spirit of the present invention including aCassegrain antenna, which includes a parabolic antenna having a feedantenna mounted behind an aperture formed in the center of the surfaceof a concave main parabolic reflector dish. The feed antenna is in frontof the main dish to direct radiation reflected from the dish backthrough the spatial light modulator and ultimately to the MMW detector129 via the electromagnetic horn 126. The electromagnetic horn 126,which can made from a suitable electrically conductive material,effectively funnels the collected MMW energy 153 to the MMW detector129. The MMW detector 129 can be a single pixel detector or multi-pixeldetector that converts the detected MMW energy 103 to an output voltagesignal. Certain commercial embodiments of an MMW detector are producedby Millitech, Ommic, Faran Technology, QuinStar Technology, Inc., orHughes Research Laboratories, LLC., just to name a few manufacturers.

The MMW detector output voltage signal in the field of view 106 iselectrically transmitted from the MMW detector 129 to the computingsystem 116 via pathway 142, which can be an electrical wire line forexample. The computing system 115 conditions the MMW detector outputvoltage signal into a metallic enhanced MMW digital image 105 (wherebymetallic objects are enhanced) that is sent over pathway 146 to bedisplayed on the display screen or monitor 130. Pathway 146 can be awireline connection between the computing system 115 and the displaydevice 130, for example. Here, an image of the panel 108 b is displayedon the display screen. In operation, any metallic enhanced MMW digitalimage 105 is displayed within the perimeter display screen 130. The MMWdigital image 105 displays the presence/image of a metallic object.Though certain embodiments envision the MMW camera 120 collecting MMWs103 passively from ambient radiation reflected and emitted from thesubject of interest, other embodiments envision an active MMW radiationsource 148 emitting MMW radiation 141 that actively reflect MMWs fromthe subject of interest. Certain embodiments envision the MMW radiationsource 148 emitting a wavelength of between 30-300 GHz with someembodiments envision the MMW radiation source 148 emitting a wavelengthcentered at 94 GHz.

Certain embodiments further envision the optical camera 122 alsopointing at the or otherwise in line with the MMW field-of-view 106 andincluded in a common camera unit 118. In the present embodiment, theoptical camera 122 is connected to the computing system 115 by way of awireline (or optionally a wireless) link 144. In this way, the computingsystem 115 can transmit an output image to the display screen 130, whichcan include an overlay of an MMW image and optical image.

As depicted, the MMW camera 120 is pointing towards the thermalcalibration panel 108 (or simply “panel”) and is separated from thepanel 108 by a stable distance 112. By stable distance 112 it is meantthat the distance between the MMW camera 120 and the panel 108 is fixedand does not change during operation. That is the MMW camera 120 and thepanel 108 are each in a fixed location during operation. Certainembodiments envision the distance 112 being between 4 feet and 50 feet,however other embodiments envision the distance being less than 20 feet.Hence, the MMW camera 120 or camera unit 118 can be mounted on a tableor a stand (e.g., tripod) and positioned at the fixed distance in frontof the panel 108. The panel 108 is configured to be maintained at aconstant and known temperature. Accordingly, certain configurationsenvision an embedded electrical heating mesh in the panel 108, a hollowregion in the panel 108 filled with water, gas, or some other kind offluid (possibly circulated to reduce thermal gradients) that iselectrically heated (or cooled) and held at a constant temperature, orsome other configuration understood by those skilled in the art. Thepanel 108 can be metal, composite, polymer based, or some other suitablematerial within the scope and spirit of the present invention. Certainembodiments envision the panel 108 being held at a temperature between70° F.-110° F., at or about the temperature of a human, just to name acouple of examples. The panel 108 can be mounted on a wall 128, asshown, or optionally on its own stand. In this embodiment, the panel 108faces the MMW camera 120 and the optical camera 122 that are embodied bythe common camera unit 118. Further in this embodiment, the MMW camera120 is at a right angle 110 to a confronting panel face 109 of the panel108. In some embodiments, the confronting panel face 109 is a flatsurface that is the largest surface of the panel 108, and in somecircumstances the only surface, that the MMW camera 120 “sees” whenthere is nothing but air between the panel 108 and the MMW camera 120.

The MMW camera 120 uses the panel 108 as the thermal calibration surfaceto calibrate against. More specifically, any drift or offset in theoutput from the MMW camera 120 can be readjusted, or ‘zeroed out’, inthe computing system 115 (or elsewhere, e.g., the MMW detector 129)based on the known temperature of the panel 108. Certain otherembodiments envision an independent heat sensitive infrared (IR) camera123 pointing at the panel 108 to collect heat information. The IR camera123 can be used in conjunction with the MMW camera 120 to calibrate theMMW camera 120. Optionally, the IR camera 123 can be independentlycalibrated against the panel 108 in the event the IR camera 123 drifts.Certain embodiments envision the IR camera 123 used to measure thetemperature of a person for purposes of identifying a person with anabove normal temperature, which could be indicative of an illness. TheIR camera 123 is connected to the computing system 115 via theconnecting link 150. In the present embodiment, the MMW camera 120, theoptical camera 122 and the IR camera 123 all receive EM waves at a rateangle 110 from the panel 108.

FIGS. 2A and 2B illustratively depict examining a person 160 as theypass between the MMW camera 120 and the panel 108 consistent withembodiments of the present invention. In this particular embodiment, thecamera unit 118 is arranged consistently with the camera unit of FIG. 1.As shown in FIG. 2A, the person 160 is about to walk between the cameraunit 118 and the panel 108, as indicated by the arrow 164. Though thepresent figure presents a person 160 on their way to walk in front ofthe camera unit 118, the person 160 is a subset of a more genericambulatory heat-producing object 160. In other words, an ambulatoryheat-producing object 160 can be an animal (such as a dog), or a heatproducing machine that can move or otherwise ambulate (such as amotorized cart or vehicle carrying one or more people). In the broadestsense, the arrangement 100 can be used with any object whether living orotherwise that passes between the panel 108 and the camera unit 118.Certain embodiments contemplate the ambulatory heat-producing object 160comprising a cover 161 that at least partially obscures theheat-producing object 160. In the present embodiment, the ambulatoryheat-producing object is a person 160 and the object cover 161 is theperson's clothing (i.e., shirt, pants, jacket, etc.). Clothing can be aweave garment, plastic or leather, just to name several well-knowngarment examples. The point being, a concealed weapon is indeedconcealed under clothing, a bag, a suitcase, or some other object cover.

With continued respect to the present arrangement 100, in certainembodiments, the MMW camera 120 and/or the IR camera 123 are calibratedagainst the panel 108 before a person 160 passes between the panel 108and the camera unit 118. This can be accomplished with the calibrationroutine 117 running on the computing system 115. The computing system115 comprising the necessary memory, microprocessors, interfaces,input/output ports and other components to execute or otherwise run thecalibration routine in addition to running other software programs likeimage conditioning and overlay software programs that are optionallystored in the computing system's local memory (not shown). Thecalibration routine 117 uses the panel 108 as a calibration baseline andis executed when a pre-determine condition is met. Examples of apredetermined condition can include two conditions: A) when there is noobject, or anything else for that matter, obscuring a clear view of thepanel 108 by the MMW camera 120 and/or the IR camera 123, and B) when asecondary calibration condition is met. In other words, condition ‘B’ isnever executed when the object cover 121 is interposed between the paneland the camera unit 118 (i.e., condition ‘A’ must be met). The secondarycondition can include: after a predetermined amount of time from a lastcalibration (e.g., after 5 or 10 minutes from the last calibration), ona predetermined schedule (e.g., at the top of every hour), after aperson/object 160 crosses the panel 108, after a certain number ofpeople/objects across the panel 108, manually, randomly activated, etc.The reason conditions ‘A’ and ‘B’ must both be met is that if the panel108 is obscured, partially obscured, has changing obscurity, then aclear calibration cannot be accomplished. Certain embodiments envisionovercoming this obstacle by calibrating a small portion of the panel 108when nothing is obscuring that small portion of the panel 108.Accordingly, in this scenario the spirit of conditions ‘A’ and ‘B’ stillhold true. One last option is that the MMW camera 120 and/or the IRcamera 123 dynamically find a calibration spot around the subject 160partially obscuring the panel 108.

FIG. 2B depicts the person 160 at least partially covered by clothing161 passing in front of the panel 108, as shown by the arrow 164. Inthis embodiment, the MMW camera 120 collects MMW 103 emitted orreflected from the person 160 (and translates into an temperatureimage), the optical camera 122 snaps an optical image of the person 160and the IR camera 123 collects heat information from the persons head162 (possibly in an IR image). At least one if not all of the images(optical, MMW and IR) can be combined and displayed 105 on the displayscreen 130. Here, the temperature from the person's head 162 is visuallyshown in a display image of the head 162 b on the display 130 (but couldalso be posted as a maximum sensed temperature value), the optical imageof the person 160 b is shown on the display 130, and metallic objects165 overlay on the person 160 b. In this particular example, the display130 shows a concealed weapon 165 under the garment 161.

FIG. 3 is a block diagram laying out the calibration scheme for the heatcamera and panel arrangement of FIGS. 2A and 2B consistent withembodiments of the present invention. As shown in step 302, an MMWcamera 120 is disposed at a fixed distance 112 (e.g., 5-20 ft. apart)from the thermal calibration panel 108 and as further shown is opposingthe panel 108. The term opposing herein is defined as an element that isdirectly in front of another element. In this case, the large flat panelface 109 is essentially opposing the MMW camera 120 (an example of“essentially” can be +/−2 degrees). That is, in this example, the largeflat panel face 109 resides in a geometric plane and the MMW camera 120is spaced away 112 from the geometric plane at essentially 90° (at aright angle 110). The panel 108 is in the MMW camera's field-of-view106. The MMW camera's field-of-view 106 is at least a single area on thewall 128 or panel 108 that can be detected by the MMW camera 120.Alternatively, the field-of-view 106 is a matrix of a plurality ofsmaller areas detected by the MMW camera 120 that are stitched togetherto make a larger area, for example, an area that is displayable on thedisplay screen 130. This can be accomplished by a plurality ofdetectors, or a motorized detector that can move slightly to cover(i.e., traverse across) the field-of-view area 106 to collect enough MMWimage areas to reconstruct a full field-of-view 106.

Step 304 is a step for maintaining the panel 108 at essentially aconstant temperature. By essentially, it is meant that the temperatureis held at a target temperature within some defined tolerance such as+/−1 degree, or +/−a fraction of a degree, for example. The temperatureof the panel 108 is detectable by an IR camera 123 (i.e., the IR wavestransmitted from the panel 108), the optical camera 122 can take(acquire) an optical image of the panel 108 the visual panel, and theMMW camera 120 can collect/detect MMWs 103 emitted and/or reflected bythe panel 108. The MMWs 103 emitted and/or reflected by the panel 108are affected by the temperature. Accordingly, the panel 108 can serve asan energy emission calibration panel 108 specifically configured forcalibrating the MMW camera 120. Certain embodiments envision the panel108 being as thin as a quarter-inch thick (or thinner) to a thickness ofup to 6 inches. Other embodiments have no specific thickness limitation,so long as the panel 108 serves its functionality within the scope andspirit of the present invention. The panel face 109 is preferably flat,however some embodiments envision a textured or slightly wavy surface.The MMW camera 120 is a fixed distance 112 from the surface of the largeflat panel face 109, which in certain embodiments serves as an energyemission calibration panel 108.

As shown in step 306, a calibration routine 117 is triggered to startcalibration on either the IR camera 123 and/or the MMW camera 120. Thecalibration routine 117 can be retained/contained in non-transientcomputer memory, such as a Solid State Drive, or some other kind ofsolid-state memory, such as a micro SD card or SDXS card, for example,that is operably connected to the microprocessor 116. The calibrationroutine 117 is executed or otherwise operates on a microprocessor 116that is either in the MMW camera 120 or in communication/linked to theMMW camera 120. Certain embodiments envision the microprocessor 116controlling the functionality of the MMW camera 120, while otherembodiments envision the microprocessor 116 cooperating with amicroprocessor (not shown) on board the MMW camera 120. Themicroprocessor 116 can further be in cooperation with at least one ofthe IR camera 123, the optical camera 122, the display 130, thecomputing device 115, and/or other peripherals or computer responsiveelements in the common camera unit 118.

The triggering step 306 can be initiated based on a number of optionalfactors as defined by the routine 117. In one embodiment, the triggeringstep 306 occurs as a result of a person 160 being scanned by at leastthe MMW camera 120 and then stepping out of the camera's field-of-view106 before another person steps in the camera's field-of-view 106. Morespecifically, when a first person 160 moves in front of the MMW camera120, the MMW camera 120 obtains an energy emission measurement in theform of collecting MMWs 103 of everything in the MMW camera'sfield-of-view 106 including the first person 160. The intensity of MMWs103 is greater over metallic objects wherein clothing does not inhibitthe emission of MMWs 103. Hence, as shown in FIG. 2B, the display screen130 shows a metallic gun-shaped object 165 hidden under the personsclothing 161. As also shown in FIG. 2B, the MMW camera 120 isessentially opposing the person 160 (i.e., the person 160 is interposedbetween the MMW camera 120 and the panel 108, or otherwise in thefield-of-view 106) in order to formulate the MMW image of the person 160b on the display 130. After the first person 160 is scanned and thenstepped out of the field-of-view 106, the calibration routine 117 caninstruct the MMW camera 120 to obtain at least one energy emissionmeasurement of the unobstructed panel 108 (e.g., measure the intensityof the MMWs emitted from the panel 106), step 312.

Optional calibration routines 117 can be triggered or otherwiseinitiated a) after a predetermined amount of time from the previouscalibration measurement, such as every half an hour, b) at specifictimes of the day, such as first thing in the morning at noon and at theend of the day, for example, c) after a certain amount of measurementstaken, such as after every five people measured, d) if the roomtemperature or lighting significantly changes, e) manually, eithercontrolled remotely or locally, f) input from a nearby panel and camerasystem that identifies a significant drift during calibration, etc.

In some embodiments after a calibration routine 117 is started, step306, step 312 of obtaining the energy emission measurement from thepanel 108 is not done until the person 160 or some object is notobstructing the panel 108, shown in the question block step 308. Ifthere is nothing obstructing the panel 108 from the MMW camera 120 inthe field-of-view, then continue on to step 312 otherwise wait until theMMW camera 120 has a clear and unobstructed view of the panel 108, step310. One embodiment of step 310 is to wait for a predetermined of timeto pass and then recheck (return to step 308), such as after a second ortwo.

With more detail to step 312, certain embodiments contemplate thecalibration routine 117 instructs the MMW camera 120 to obtain at leastone energy emission measurement from the panel 108 only when the panel108 is not obstructed from the field-of-view 106. In other words,despite which calibration scheme is used, there must be no person 160 orsome other ambulatory object interposed between the panel 108 and theMMW camera 120 because the MMW camera 120 needs to be able to fully seethe panel 108 in order to properly calibrate. However, certain otherembodiments envision the panel 108 divided into quadrants or smallerareas by which the MMW camera 120 can calibrate against a smallidentifiable area on the panel 108 instead of the entire panel 108. Forexample, if the panel 108 was divided into 16 rectangles or partitions(either mapped by the MMW camera 120 or processor 116, or physicallydistinguishable sections on the panel 108), and if at least one of therectangles is not obstructed, then it is possible to calibrate againstat least one of the unobstructed rectangle partitions.

Another embodiment of the panel 108 is a panel that is divided into aplurality of regions/sections (at least two regions/sections), such asrectangles, wherein each of the regions/sections is held at a differenttemperature. The sections held at a different temperature will allow theMMW camera 120 (or IR camera 123) to calibrate the voltage gain (slope)as well as the offset. Optionally, the panel 108 can have at least tworegions/sections made of different materials that each have a differentemissivity, which can assist in various calibration routines for the MMWcamera 120 including slope and offset.

Once an energy emission measurement is taken from the panel 108, abaseline emission value is readjusted in the MMW camera 120, step 314.The baseline emission value (the baseline of the emission energycollected from the panel 108) corresponds or is otherwise matched to theenergy emission of the panel 108 held at the constant temperature. Inother words, the MMW camera 120 is calibrated against the calibrationpanel 108. This calibration scheme 117 corrects for driftingmeasurements taken by the MMW camera 120 to provide confidence that datataken by the MMW camera 120 is accurate.

It should be appreciated that steps 302-314 can be equally applied tothe IR camera 123 whereby instead of MMWs 103 collected or otherwisesensed by the MMW detector/sensor 129, infrared energy is sensed by theIR camera 123. The IR camera 123 can be further used to take temperaturemeasurements of a person's head 162, which if above or below normal canbe an indication of a sick person. Temperature data can be presented onthe display 130, or an alarm can be triggered if a person's temperatureis above or below a margin of tolerance (e.g., a fever of above 100°F.), just to name several reporting examples. For obvious reasons, theIR camera 123 needs to be accurate to be confident in temperaturemeasurements taken of a person's head 162. Hence, the IR camera 123 iswell adapted for the calibration scheme using the temperature controlledpanel 108. Images of data taken with the IR camera 123 can besuperimposed over the images of the MMW camera 120 on the display screen130, or other capable display device/s. An optical image of thefield-of-view 106 superimposed over the MMW camera image and/or the IRcamera image can further enhance an end users understanding of thatwhich is displayed. A skilled artisan will readily appreciate that alldata can be stored digitally and retrieved for later use or transmittedto other computer systems in a multitude of ways known to those skilledin the art.

With reference back to the MMW camera 120 and with reference to FIG. 2B,after the calibration step 314, the MMW camera 120 is available fortaking a new image of a second person passing in the MMW camerafield-of-view 106, step 316. In this way, MMWs 103 emitted and/orreflected from the person 160, who in this example is wearing a garment161, is collected by the camera 120. The data is then sent to thecomputing system 115. The display 130 illustratively depicts an image ofthe person 160 b (along with the image of the person's head 162 b) andan image of a gun shaped metallic object 165 on the person's body 160,step 318. The gun shaped metallic object 165 is obscured or otherwisevisibly concealed by the persons garment 161 when viewed by an onlookeror optical camera, for example. However, the MMW's 103 easily penetratethrough the garment 161 and are therefore picked up by the MMW detector129 to display an image of the gun shaped object 165 on the displayscreen 130. Certain other algorithms that can run on the computingsystem 115 include shape recognition algorithms to identify concealedweapons such as guns, particular kinds of guns, knives, bombs, or otherkinds of metallic weaponry that can be concealed. Obviously, thesealternate algorithms can be stored to nonvolatile memory (not shown)cooperating with the computing system 115. Some embodiments envision ifa weapon is discovered on the person 160, an alarm will be set off(whether visually on the display 130, or a light, a siren, by way of anelectronic notification sent to an authority or end user, etc., or somecombination thereof).

FIG. 4 is a line drawing of yet another calibration arrangement 400 ofthe present invention with a plurality of MMW cameras consistent withembodiments of the present invention. As shown, an array of MMW cameras420 point towards the panel 108. The MMW cameras 420 are essentiallyopposing the large panel face 109 at a fixed distance 112, which incertain embodiments is 5-20 ft. The MMW cameras 120A-120D collectivelycomprise the field-of-view 106 either by virtue of being spread apart orby slightly tipped in a different region of the field-of-view 106. Inthis way, an MMW image displayed on the display screen 130 can beconstructed, assembled or otherwise stitched together from each of theindividual MMW cameras 120A-120D. Certain embodiments envision a matrixof MMW cameras instead of a single array of MMW cameras 420. Forexample, one or more similar arrays of MMW cameras disposed below thedepicted array of MMW cameras 420, such as a matrix of 20 MMW cameras (5stacked arrays) that collectively can make up the field-of-view 106.Each of the MMW cameras 120A-120D are linked to the computing system 115by way of a wireline 442. As in the other figures, the computing system115 feeds information into the display screen 130. An image of the panel108 b, which corresponds to the panel 108, is displayed on the displayscreen 130. For purposes of simplicity, a housing is not showncontaining the array of MMW cameras 120A-120D, however in reality one ormore housings can be employed. It should be appreciated that othercameras, such as the IR camera 123 and optical camera 122 can be used inthe present arrangement 400 in a manner described in conjunction withthe previous figures. It should also be appreciated that the algorithmsdescribed in conjunction with the previous figures can be equallyapplied to the present embodiment.

With the present description in mind, below are some examples of certainembodiments illustratively complementing some of the methods andapparatus embodiments to aid the reader. The elements called out beloware examples provided to assist in the understanding of the presentinvention and should not be considered limiting.

In that light, certain embodiment contemplate a camera calibrationarrangement 100 comprising a heat sensing camera 120 having afield-of-view 106 and a heat calibration panel 108 comprising at leastone temperature that is essentially constant. The word ‘having’ as usedherein is to be interpreted as synonymous with ‘comprising’. The heatcalibration panel 108 is in the field-of-view 106 and is disposedessentially at the right angle 110 to a confronting panel face 109 ofthe heat calibration panel 108. The heat calibration panel 108 is at astable or otherwise fixed distance 112 away from the heat sensing camera120. An object cover 161, such as a shirt or some other garment, isconfigured to cover a portion of an ambulatory heat producing object160, which can be a person 160 either walking or on a cart. Theambulatory heat producing object 160, and by defacto, the object cover161 is defined in a first location of FIG. 2A that is interposed betweenthe heat sensing camera 120 and the heat calibration panel 108 and theobject cover 161 in a second location of FIG. 2B that is not in thefield-of-view 106. A microprocessor 116 that is configured to execute acalibration routine 117 that uses the heat calibration panel 108 as acalibration baseline when a predetermined condition is met. Thecalibration routine 117 is never executed when the object cover 161 isin the first location.

The camera calibration arrangement 100 further contemplating wherein thestable distance 112 is at least 5 feet away from the camera 120.

The camera calibration arrangement 100 further envisioning wherein theheat calibration panel 108 is mounted on a wall 128.

The camera calibration arrangement 100 further pondering wherein thedistance 112 does not change.

The camera calibration arrangement 100 further comprising a heat imageroutine 117 that is configured to obtain a heat signature of theambulatory heat producing object 160 via the heat sensing camera 120.

The camera calibration arrangement 100 further imagining wherein theheat calibration panel 108 comprising a surface area 109 viewable to theheat sensing camera 120 that is greater than 2 feet squared.

The camera calibration arrangement 100 further considering wherein theheat sensing camera 120 is a millimeter wavelength camera.

The camera calibration arrangement 100 further envisioning wherein theheat sensing camera 120 senses infrared and/or emissivity.

The camera calibration arrangement 100 further pondering wherein thepredetermined condition is met after the object cover 161 crossesbetween the heat sensing camera 120 and the heat calibration panel 108,after a predetermined amount of time, during a predetermined timeschedule, manually activated either remotely or locally, or randomlyactivated.

The camera calibration arrangement 100 further contemplating wherein theheat sensing camera 120 comprises the microprocessor 116.

The camera calibration arrangement 100 further imagining wherein theheat sensing camera 120 is configured to distinguish at least onemetallic 165 behind the object cover 161. This can further be where themetallic object 165 is a weapon.

The camera calibration arrangement 100 further envisioning wherein theambulatory heat producing object 160 is a human being.

Yet another embodiment of the present invention contemplates cameracalibration method comprising: providing an MMW camera 120 disposed at afixed distance 112 from an energy emission calibration panel (panel) 108and opposing the panel 108, the panel 108 in a field-of-view 106 of theMMW camera 120. The panel 108 being maintained at essentially a constanttemperature. Triggering a calibration routine for the MMW camera 120that operates on a processor in communication with the MMW camera 120.After the triggering step, obtaining an energy emission measurement ofthe panel 108 via the MMW camera 120 only when the panel 108 is notobstructed from the field-of-view 106. After the obtaining step,calibrating the MMW camera 120 by adjusting an energy emissionmeasurement level for the MMW camera 120 to match the energy emission.After the adjusting step, the MMW camera 120 acquiring a metal objectsignature from a metal object that is on a person's body 160, the metalobject is between the person's body 160 and the MMW camera 120, themetal object is covered under clothing 161 that covers at least aportion of the person's body 160. After all of these steps, visuallydisplaying the metal object signature on a display screen linked to theMMW camera 120.

The camera calibration method embodiment further imagining wherein thefixed distance is between 5 feet and 20 feet.

The camera calibration method embodiment further considering wherein thepanel 108 is mounted on a wall and the MMW camera 120 is affixed to astand. The stand being a table or a tripod or something like that.

The camera calibration method embodiment further pondering wherein theobtaining step happens between when a second person's body is interposedbetween the MMW camera 120 and the panel 108 and the person's body isinterposed between the MMW camera and the panel 108, the triggering stepoccurs as a result of the person's body passing in between the MMWcamera 120 and the panel 108. This can further be wherein the triggeringstep also occurs as a result of the second person's body passing betweenthe MMW camera 120 the panel 108. Optionally, this can further bewherein the triggering step occurs after a predetermined amount of timehas lapsed. Yet in another option, the method can further comprise aninfrared (IR) camera 123 linked with the MMW camera 120; the IR camera123 collecting infrared radiation from the panel 108; calibrating the IRcamera 123 from the infrared radiation; collecting a heat signature ofat least a portion of the person's body 160 when in the field-of-view106, the IR camera 123 sharing an overlapping IR field-of-view with thefield-of-view 106. Still in another option, the method can furthercomprise an optical camera 122 linked with the MMW camera 120, the MMWcamera 120 collecting and optical image of the person's body 160 andsuperimposing an image of the person's body 160 with the metal objectsignature on a display screen.

In yet another embodiment of the present invention, an MMW wave sensingcamera calibration arrangement 100 is envisioned comprising an MMWcamera 120 disposed at a fixed distance from an energy emissioncalibration panel (panel) 108, the MMW camera 120 is opposing a frontface 109 of the panel 108. The MMW camera 120 further defines afield-of-view 106 that encompasses the panel 108. The calibration panel108 is at essentially a constant temperature. The MMW camera 120 havingan MMW sensor 129 comprising a baseline emissivity value correspondingto the panel 108. A microprocessor 116 that is linked to the MMW camera120 and non-transient computer memory containing a calibration routinethat is configured to reset the baseline only when no object obstructsthe panel 108 in the field-of-view 106. A visual display 130 that islinked to the MMW camera 120 and configured to display an MMW signatureof a metal object that is disposed on a person's body 160 when theperson's body 160 is in the field-of-view 106, the metal objectconcealed by clothing 161 worn over the person's body 160.

Still another embodiment of the present invention contemplates acalibration arrangement 400 comprising: an array of MMW sensing cameras420 having a collective field-of-view 106, the array is essentially at aright angle 110 to a plane defined by a heat calibration panel 108. Thepanel 108 comprising at least one temperature that is essentiallyconstant wherein the heat calibration panel 108 is in the field-of-view106. The heat calibration panel 108 comprising a confronting surfacearea 109 that is essentially maximally viewed by the array of heatsensing cameras 420. The heat calibration panel 108 is disposed at astable distance 112 away from the array 420. The arrangement furtherincluding an object cover 161 configured to cover a portion of anambulatory heat producing object 160, such as a person. The object cover161 when in a first location is interposed between the array of heatsensing cameras 420 and the heat calibration panel 108 and when theobject cover 161 is in a second location, it is not in the field-of-view106. A microprocessor 116 is configured to execute a calibration routine117 that uses the heat calibration panel 108 as a calibration baselinefor each of the array of heat sensing cameras 420 when a predeterminedcondition is met, the calibration routine 117 is never executed when theobject cover 161 is in the first location.

The above sample embodiments should not be considered limiting to thescope of the invention whatsoever because many more embodiments andvariations of embodiments are easily conceived within the teachings,scope and spirit of the instant specification.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with the details of thestructure and function of various embodiments of the invention, thisdisclosure is illustrative only, and changes may be made in detail,especially in matters of structure and arrangement of parts within theprinciples of the present invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed. For example, though an integrated light source 148 isdepicted with the camera system 118, it could just as easily be externalas can be the display 130 or other elements shown on or within thecamera system 118 without departing from the scope and spirit of thepresent invention. Another example is the antenna 124, horn 125 and MMWdetector 129 could include more or less elements to accommodateadvancements in the art while still maintaining substantially the samefunctionality without departing from the scope and spirit of the presentinvention. Further, the term “one” is synonymous with “a”, which may bea first of a plurality.

It will be clear that the present invention is well adapted to attainthe ends and advantages mentioned as well as those inherent therein.While presently preferred embodiments have been described for purposesof this disclosure, numerous changes may be made which readily suggestthemselves to those skilled in the art and which are encompassed in thespirit of the invention disclosed and as defined in the appended claims.

What is claimed is:
 1. A camera calibration arrangement comprising: aheat sensing camera having a field-of-view; a heat calibration panelcomprising at least one temperature that is essentially constant, theheat calibration panel is in the field-of-view and is disposedessentially at the right angle to a confronting panel face of the heatcalibration panel, the heat calibration panel is at a stable distanceaway from the heat sensing camera; an object cover configured to cover aportion of an ambulatory heat producing location, the object cover in afirst location that is interposed between the heat sensing camera andthe heat calibration panel and the object cover in a second locationthat is not in the field-of-view; and a microprocessor that executes acalibration routine that uses the heat calibration panel as acalibration baseline when a predetermined condition is met, thecalibration routine is never executed when the object cover is in thefirst location.
 2. The single camera calibration arrangement of claim 1wherein the stable distance is at least 5 feet away from the camera. 3.The single camera calibration arrangement of claim 1 wherein the heatcalibration panel is mounted on a wall.
 4. The single camera calibrationarrangement of claim 1 wherein the distance does not change.
 5. Thesingle camera calibration arrangement of claim 1 further comprising aheat image routine that is configured to obtain a heat signature of theambulatory heat producing location via the heat sensing camera.
 6. Thesingle camera calibration arrangement of claim 1 wherein the heatcalibration panel comprising a surface area viewable to the heat sensingcamera that is greater than 2 feet squared.
 7. The single cameracalibration arrangement of claim 1 wherein the heat sensing camera is amillimeter wavelength camera.
 8. The single camera calibrationarrangement of claim 1 wherein the heat sensing camera senses infraredand/or emissivity.
 9. The single camera calibration arrangement of claim1 wherein the predetermined condition is met after the object covercrosses between the heat sensing camera and the heat calibration panel,after a predetermined amount of time, during a predetermined timeschedule, manually activated either remotely or locally, or randomlyactivated.
 10. The single camera calibration arrangement of claim 1wherein the heat sensing camera is configured to distinguish at leastone metallic object behind the object cover.
 11. The single cameracalibration arrangement of claim 10 wherein the metallic object is aweapon.
 12. A camera calibration method comprising: providing an MMWcamera disposed at a fixed distance from an energy emission calibrationpanel (panel) and opposing the panel, the panel in a field-of-view ofthe MMW camera; maintaining the panel at essentially a constanttemperature; triggering a calibration routine for the MMW camera thatoperates on a processor in communication with the MMW camera; after thetriggering step, obtaining an energy emission measurement of the panelvia the MMW camera only when the panel is not obstructed from thefield-of-view; after the obtaining step, calibrating the MMW camera byadjusting an energy emission measurement level for the MMW camera tomatch the energy emission; after the adjusting step, the MMW cameraacquiring a metal object signature from a metal object that is on aperson's body, the metal object is between the person's body and the MMWcamera, the metal object is covered under clothing that covers at leasta portion of the person's body; visually displaying the metal objectsignature on a display screen linked to the MMW camera.
 13. The cameracalibration method of claim 12 wherein the fixed distance is between 5feet and 20 feet.
 14. The camera calibration method of claim 12 whereinthe panel is mounted on a wall and the MMW camera is affixed to a stand.15. The camera calibration method of claim 12 wherein the obtaining stephappens between when a second person's body is interposed between theMMW camera and the panel and the person's body is interposed between theMMW camera and the panel, the triggering step occurs as a result of theperson's body passing in between the MMW camera and the panel.
 16. Thecamera calibration method of claim 15 wherein the triggering step alsooccurs as a result of the second person's body passing between the MMWcamera the panel.
 17. The camera calibration method of claim 15 whereinthe triggering step occurs after a predetermined amount of time haslapsed.
 18. The camera calibration method of claim 15 further comprisingan infrared (IR) camera linked with the MMW camera, the IR cameracollecting infrared radiation from the panel, calibrating the IR camerafrom the infrared radiation, collecting a heat signature of at least aportion of the person's body when in the field-of-view, the IR camerasharing an overlapping IR field-of-view with the field-of-view.
 19. Thecamera calibration method of claim 15 further comprising an opticalcamera linked with the MMW camera, the MMW camera collecting and opticalimage of the person's body and superimposing an image of the person'sbody with the metal object signature on a display screen.
 20. An MMWwave sensing camera calibration arrangement comprising: an MMW cameradisposed at a fixed distance from an energy emission calibration panel(panel), the MMW camera is opposing a front face of the panel; the MMWcamera comprising a field-of-view that encompasses the panel; thecalibration panel is at essentially a constant temperature; an MMWsensor comprising a baseline emissivity value corresponding to thepanel; a microprocessor linked to the MMW camera; non-transient computermemory containing a calibration routine that is configured to reset thebaseline only when no object obstructs the panel in the field-of-view; avisual display linked to the MMW camera configured to display an MMWsignature of a metal object that is disposed on a person's body when theperson's body is in the field-of-view, the metal object concealed byclothing worn over the person's body.